Model 2520 User’s Manual
Data Flow
C-3
SENS1, SENS2, and SENS3
The SENS1 block represents the basic laser diode voltage readings. The SENS2 and
SENS3 blocks represent the basic measured current readings for photodiode detector #1
and photodiode detector #2 respectively. If the filter is enabled, the readings will be fil-
tered. The SENS blocks also measure time for the timestamp. Readings can be taken
directly from one of the SENS blocks with one of the DATA? queries when the unit is in
idle.
INIT
When the INITiate command is sent, the programmed number of source and measure
operations are performed, and the respective data is temporarily stored in a reading buffer.
For example, if 20 source and measure operations were performed, then 20 sets of data
will be stored in the reading buffer. Data from this buffer is then routed to other enabled
data flow blocks.
NOTE
If the Model 2520 is in the fixed mode, it will process one set of readings per
trigger. If the unit is in the sweep mode, it will process one sweep per trigger.
The number of readings per sweep depends on programmed sweep parameters.
The data that is output by the read commands (FETCh? and READ?) depend on which
data elements are selected. With all elements selected, available data includes both voltage
and current measurements, source values, as well as the timestamp and status information.
See
After all source and measure operations are completed, the Model 2520 returns to the idle
state. The data stored in the reading buffer will remain there until data from another
source-measure cycle overwrites the buffer. Data in the reading buffer is lost if the Model
2520 goes to the local state (REM annunciator off).
NOTE
With no data in the reading buffer, sending the FETCh? and
CALCulateX:DATA? commands to read data will display the
message “Data corrupt or stale.”
FETCh?
This command is used to read processed data from the reading buffer. If, for example,
there are 20 data sets stored in the reading buffer (in the sweep mode), then all 20 data sets
will be sent to the computer when FETCh? is executed. Note that FETCh? does not affect
processed data in the reading buffer. Thus, subsequent executions of FETCh? acquire the
same data.
Summary of Contents for 2520
Page 250: ...A Specifications ...
Page 254: ...B StatusandErrorMessages ...
Page 262: ...C DataFlow ...
Page 266: ...D IEEE 488BusOverview ...
Page 281: ...E IEEE 488andSCPI ConformanceInformation ...
Page 285: ...F MeasurementConsiderations ...
Page 308: ...G GPIB488 1Protocol ...
Page 312: ...H ExamplePrograms ...
Page 317: ...I ContinuousPulseMode ...